Why your iPhone photos will not open
Since iOS 11, iPhones have saved photos as HEIC rather than JPEG. It is a genuinely better format: roughly half the file size for the same picture, plus support for depth data, live photos and wider colour. Apple switched because it saves an enormous amount of storage.
The trouble is that almost nothing outside Apple can read it. Windows needs a codec from the Microsoft Store that used to cost money. Most websites reject the upload. Older versions of Photoshop, most job-management and accounting software, plenty of email clients, print shops, insurance portals and council planning uploaders all refuse it.
So you have a perfectly good photo, taken to send to somebody, that the thing you need to send it to will not accept. Converting to JPG fixes that permanently, because JPG has been universally supported since the 1990s.
Stopping it happening again
On the iPhone itself: Settings, Camera, Formats, Most Compatible. That makes the phone shoot JPEG from then on, at the cost of roughly double the storage per photo. It does not convert the photos you already have.
There is also Settings, Photos, Transfer to Mac or PC, set to Automatic, which converts to JPEG as it copies off the phone. Set to Keep Originals and you get the HEIC files, which is how most people end up here.
The decoder runs on your machine too
This is the part that makes this tool unusual. Browsers other than Safari cannot decode HEIC at all, which is how every other HEIC converter ends up uploading your photos to a server: it is far easier to decode them there.
Your photos are the most personal files you own. Uploading a camera roll to a free website whose business model you have not read is a genuinely bad idea, and most of those sites keep the files for hours afterwards.
Instead, this fetches a WebAssembly build of libheif, the open-source decoder, and runs it in your browser. It is about 3MB, it downloads once, and it only downloads when you actually convert something. Opening this page costs you nothing.
And if you are on Safari or a Mac, it downloads nothing at all, because Apple's browsers read HEIC natively. The people most likely to have HEIC files are the ones who never pay the download.
Expect the files to get bigger
HEIC is about twice as efficient as JPEG, so the same photo comes out roughly twice the size. A 2MB HEIC becomes a 4MB JPG carrying exactly the same picture.
That is not the converter doing something wrong. It is the price of a file that everything can open, and it is the whole reason Apple switched formats in the first place. If size matters, there is a longest-side setting here: 2048 pixels is more than enough for anything on a screen and will bring the file well under the original.
What does not survive the conversion
Live Photos lose their motion, because a JPG is a single frame. Depth data used for portrait mode is dropped. HDR gain maps are flattened to standard range. Burst sequences become individual stills.
Keep the originals if any of that matters to you. Converting is a one-way trip, and you cannot get depth or motion back out of a JPG.
No limits, because there is nothing to limit
No cap on how many photos, no maximum file size, no daily quota, no watermark and no account. Other converters meter it because decoding on their servers costs them money. This costs us nothing because it happens on your machine, so there is nothing to meter.
Your photos never leave the machine they are on
The photos stay on your machine and are discarded when you close the tab. Nothing is uploaded and nothing is logged.
Common questions
Why won't my iPhone photos open on my computer?
Because since iOS 11 the iPhone saves photos as HEIC rather than JPEG, and almost nothing outside Apple can read that format. Windows needs a codec from the Microsoft Store that used to cost money, and many websites, older Photoshop versions, job-management and accounting software, email clients and print shops all reject the upload outright.
How do I stop my iPhone taking HEIC photos in the first place?
Go to Settings, Camera, Formats and choose Most Compatible. That makes the phone shoot JPEG from then on, at the cost of roughly double the storage per photo. It only affects photos taken afterwards, not the ones already on your phone.
Does converting HEIC to JPG upload my photos anywhere?
No. Browsers other than Safari cannot decode HEIC at all, which is why most HEIC converters upload your photos to a server to do the decoding there. This tool instead downloads a small WebAssembly build of the open-source libheif decoder and runs it in your own browser, so your photos never leave your device.
Why do my converted JPG files come out bigger than the original HEIC?
Because HEIC is about twice as efficient as JPEG, so the same picture takes roughly double the space as a JPG. A 2MB HEIC becomes about a 4MB JPG of the same photo. That is the price of a format everything can open, and it is why Apple switched to HEIC in the first place.
What do I lose when I convert a Live Photo or a portrait shot to JPG?
The motion in a Live Photo, because a JPG is a single frame. Depth data used for portrait mode is dropped, HDR gain maps are flattened to standard range, and burst sequences become individual still images. Keep the originals if any of that matters, because converting is a one-way trip.
Is there a limit on how many photos I can convert?
No cap on the number of photos, no maximum file size, no daily quota, no watermark and no account. Other converters meter usage because decoding on their own servers costs them money; this runs on your machine, so there is nothing for them to meter.